In the field of business-use water-heater systems, multi-water-heater systems that use a plurality of instantaneous gas water heaters have recently been replacing water-heater systems that combine a boiler and a storage tank. A multi-water-heater system has various advantages: for example, when one water heater fails, the other water heaters can operate as a backup to continue supply of hot water; a special machine room is not necessary and it is relatively easy to bring in, carry out and replace component devices; nor are special engineers, such as boiler engineers, necessary, as one can operate the system only with simple remote-control operations.
The present applicant has developed such multi-water-heater systems and has disclosed some in Patent Documents 1 and 2, listed below, for example.
Further, Patent Document 3, also listed below, discloses a remote management system in which a relay adapter (communication relay unit) that works as a relay between heat source equipment and a management center is provided for transmitting various types of information about the heat source equipment to the management center and manages it remotely, where the relay adapter of the remote management system determines whether a communication abnormality is located between the heat source equipment and relay adapter or between the relay adapter and conversion transmission board and indicates the result of this determination on an LED indicator using various lighting modes (see Patent Document 3, paragraph 0098, and FIG. 9). Further, the relay adapter includes non-volatile memory that stores information associated with the heat source equipment obtained from the heat source equipment and, in response to a request from the management center, is capable of transmitting the information stored in the non-volatile memory to the management center.
The relay device (36) described in Patent Document 3 is a means for selecting the relay adapter (28) or microcomputer meter (42) to be connected to the conversion transmission board (38) (paragraph 0041) and thus is a switch means, rather than a relay for communications for transmission-protocol conversion, for example.